ConfigureSystemFontProvider procedure

Installs a process-wide application font mapper through PDFium's native system-font callback interface

Call it before the first LoadLibrary or before opening any TPdf document

Calling it while PDFium is loaded raises EPdfError so native font handles can never outlive their provider configuration

IPdfSystemFontProvider.ResolveFont receives the requested face, weight, italic state, charset, and pitch family

Return True with a face name, full TrueType, TrueType Collection, or OpenType byte array, charset, and optional TTC index

The provider may run on PDFium worker threads and must be thread-safe

Exceptions are contained at the native callback boundary and count as failed provider responses

TPdfSystemFontPolicy.Default allows native fallback and face substitution, limits each supplied font to 64 MiB, and retains up to 32 request results in a bounded LRU cache

Set AllowDefaultFallback to False when every missing-font decision must be made by the application

Set AllowFaceSubstitution to False to reject a response whose face name differs from the requested name

A zero MaxCacheEntries disables request caching

ConfigureSystemFontCacheGovernor can additionally place retained font bytes under a shared cross-cache budget

GetSystemFontProviderStatistics returns a TPdfSystemFontStatistics snapshot covering Configured, Installed, MapRequests, CacheHits, ProviderHits, DefaultFallbackHits, RejectedProviderResponses, FailedRequests, FontDataRequests, ActiveHandles, CachedFonts, CachedFontBytes, and CacheEvictions

The snapshot is safe to query while PDFium is rendering

Call UnloadLibrary before ClearSystemFontProvider

Clearing resets the provider, policy, cache, and statistics

Calling it while PDFium remains loaded raises EPdfError